/**
 * Created by thomas on 2017/5/17.
 */
/**
 * Created by thomas on 2017/5/7.
 */
/**
 * Created by thomas on 2017/5/2.
 */

const overscroll = function(el,contain) {
    el.addEventListener('touchstart', function() {
        let top = el.scrollTop
            , totalScroll = el.scrollHeight
            , currentScroll = top + el.offsetHeight;
        //If we're at the top or the bottom of the containers
        //scroll, push up or down one pixel.
        //
        //this prevents the scroll from "passing through" to
        //the body.
        if(top === 0) {
            el.scrollTop = 1;
        } else if(currentScroll === totalScroll) {
            el.scrollTop = top - 1;
        }
    });
    el.addEventListener('touchmove', function(evt) {
        //if the content is actually scrollable, i.e. the content is long enough
        //that scrolling can occur
        if(el.offsetHeight < el.scrollHeight){
            evt._isScroller = true;
        }

    });
// overscroll(document.querySelector('.scroll'));
   contain.addEventListener('touchmove', function(evt) {
        //In this case, the default behavior is scrolling the body, which
        //would result in an overflow.  Since we don't want that, we preventDefault.
        if(!evt._isScroller) {
            evt.preventDefault();
        }
    });
}

export default overscroll;
